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1、AbstractASupervisionControlDataAcquisition(SCADA)systemisacommunicationcontrolsystemusedfmonitingoperationmaintenanceofenergyinfrastructuregrids.ComparedwithtraditionalapplicationsaSCADAsystemhasaharshdeadlinefcriticalta

2、sks.ThereisspecialtimeconstraintftherealtimedatabaseusedinaSCADAsystem.TherealtimedatabaseinSCADAextendstraditionaldatabasetoincludeinmemydatabase.Suchrealtimedatabasemanagementaredesignedtooperateintheharshenvironmentof

3、realtimesystemswithstrictrequirementsfresourceutilizationarereadytoprovidetheperfmancereliabilityrequiredbyreallifeapplications.Inthispaperthemainprincipleofrealtimedatabasehasbeenintroduced.Itsimplementationinpowersyste

4、mSCADAisdiscussedasampledatabaseisbrieflyintroduced.Keywds:SCADARealtimeDatabaseInmemyDatabase1.IntroductionASupervisionControlDataAcquisition(SCADA)systemisacommunicationcontrolsystemusedfmonitingoperationmaintenanceofe

5、nergyinfrastructuregrids.ComparedwithtraditionalapplicationsaSCADAsystemhasaharshdeadlinefcriticaltasks.Ithasdifferentacteristics:thesystemmustmaintainmassivesharingdatacontroldataalsoeachrealtimetaskofaSCADAsystemhasari

6、goustimerequirementwhilethedatafanalysisprocessingistimevariant.Realtimedatahasashtlifecyclefexampleallthedataofremotemeasurementsremotesignalsmustbeupdatedevery5secondsthedecisionderivationbasedonobsoletedataisinvalid[1

7、2].TherefethereisspecialtimeconstraintfthedatabaseusedinaSCADAsystem.Thedatabaseshouldbeabletoprocesspersistentstaticdatamaintaintheintegrityconsistencyofthemshouldbeabletodealwiththedynamicdatawithinitstimeconstraintsdu

8、ringprocessingensuretheconcurrenceefficiencyofdataaccess[34].Thiskinddatabaseisclassifiedasarealtimedatabase.ThedataitsprocessingofarealtimeSCADAdatabasehaveharshtimeconstraints.Theaccuracynotonlyreliesonthebusinesslogic

9、alresultbutalsoisdecidedbywhetherthelogicalderivationcompletesincertaininterval.TherefeweneedtocombinerealtimetheywithtraditionaldatabasetechnologytorealizearealtimedatabaseinaSCADAsystem.2.TechnicalIssuesinRealtimeDatab

10、aseImplementationLiketraditionaldatabasemanagementsystemsrealtimedatabasesystems(RTDBMS)serveasrepositiesfdataprovideefficientstageloadmanipulationofdata.TheymustbeequippedwithbasicfunctionsofgeneralDBMS.Meovertomeetthet

11、empalrequirementsofthemanageddatatimingconstraintsontransactionsperfmancetherealtimedatabaseshouldsupptonlinequerylocationdeletionion.Aninmemydatabaseisoftenusedtoachievethespeedrequirement.Functionalitiesofarealtimedata

12、basecanbesummarizedasbelow[34]:?ProvidesplatfmtosharedatawithentireEnergyManagementSystem(EMS)?Providesopendatabaseinterfacerealizesthefunctionofdatabasesuchasfastloadinputdeletioninquiryloadaccess?Providessnapshothistyd

13、atastagecopyreutilization?Providesvaliditycheck?ProvidessecurityprotectionTorealizethefunctionalitiesofarealtimedatabasethereareseveraltechnicalissuesinrealtimedatabaseimplementationaselabatedbelow.2.1RealtimeDatabaseMod

14、elDesignImplementationArelationaldatabaseisgoodatdatarepresentationmanagement.WhenarelationaldatabaseisusedinaSCADAsystemwhichisalargescalecomplicatedrealtimesystemwiththefunctionsofdatamanagementmonitinganalysisdecision

15、someshtcomingsOverviewofRealTimeDatabaseManagementSystemDesignfPowerSystemSCADASystemJianWuYongChengNoelN.SchulzDepartmentofElectricalComputerEngineeringMississippiStateUniversity62042440169006$20.00?2006IEEE.Authizedlic

16、enseduselimitedto:HuaiyinInstituteofTechnology.DownloadedonMarch102010at21:37:30ESTfromIEEEXple.Restrictionsapply.Indertosupptthefunctionalitiesabovearealtimedatabasecanbeanintegrationoftraditionalrelationaldatabaseinmem

17、ydatabase.ThegeneralarchitectureisshowninFigure1[12].ItincludestherealtimetaskdispatchmanagementinmemydatabaseIOdispatchtherelationaldatabase.RealtimetaskdispatchmanagementRealtimeapplicationInmemorydatabaseDatabasemodel

18、managementRealtimeresourcemanagementDataoperationNetworkcommunicationIODispatchRelationalDatabaseFigure1.RealtimedatabasesystemstructureTherealtimetaskdispatchmanagementprovidescodinationbetweenactivitiesofrealtimetaskst

19、oaccesstherealtimedatabase.TheinmemydatabaseholdsthemaineffectiverangeofdatainthememytoavoiddiskIOduringrealtimebusinessimplementationenhancesimplementationefficiency.Itisthecepartofthedatabase.Thedetailedelabationwillbe

20、presentedinsection5.Therelationaldatabaseinthisarchitecturecanbeusedasinterfaceffurtherdevelopmentaswellasstagemediumfinmemydatabase.TheIOdispatchisresponsiblefdatasynchronizationofmemydatabaserelationaldatabasethroughwh

21、ichtherealtimedatabasecanbeseamlesslyintegratedwithtraditionaldatabase.4.1RealtimeTaskDispatchManagementInSCADAtherearenestingcommunicationcooperationrelationsamongrealtimetasks.Thederiveddataobjectofataskispossiblythein

22、putdataobjectofanothertask.Thedataobjectthetaskaredependentoneachother.Itisnecessarytocodinateactivitiesofrealtimetasks.Thetaskdispatchmanagementshouldprovidethefollowingfunctionstosharedatabaseresourcescodinateconflict[

23、8]:?Startstoptaskatfixedtime?Allowsetupconditionstotriggertask?Specifyexecutionsequenceamongtasks?Constraintheinstancenumberofglobaltask.4.2IOdispatchTheIOdispatchisresponsiblefdatasynchronizationofinmemydatabasewithrela

24、tionaldatabase.Theinmemydatabasehasaonetoonerelationwithrelationaldatabase.Thedatainarelationaldatabaseneedstobeautomaticallysynchronizedwithinmemydatabase.Itisimptanttodecidewhentowritethedatainaninmemydatabasetoarelati

25、onaldatabasewhentoexptthedatainarelationaldatabasetoinmemydatabase.Thereisnogeneralsolution.Onepossiblewayistoprovidemethodsofperiodicalupdatefcedupdateindualdirectionbetweenarelationaldatabaseaninmemydatabase.Fdifferent

26、applicationsthetwomethodscanbeusedfdifferentobjectsaccdingtotheiracteristics.5.InMemyDatabaseAninmemydatabaseisthecepartofarealtimedatabase.Itfunctionscoverthedatabasedatamodeldataoperationrealtimeresourcemanagementwkcom

27、munication.Thetraditionaldatabaseisadiskbaseddatabase.Itsprocessingtimeisindeterministicbecauseitinvolvesthediskaccessdatatransferbetweeninternalexternalmemybuffermanagementwaitinglistlockmanagement.Thispropertymakestrad

28、itionaldatabasesystemunabletoachievetherequirementsofrealtimetransactionsthatareofhighefficiencytimedeterministic.TherefetheintroductionofinmemydatabasemakesitpossibletohavemosttransactionshappeninthememywhichavoidsdiskI

29、Oduringrealtimetransactionsreducesuncertaintyenhancesefficiency[68].5.1DataModelofDatabaseAninmemydatabaseastheextensionofarelationaldatabasehassimilaritywitharelationaldatabase.Atableisthekeypartofaninmemydatabase.Atabl

30、edescribesagroupdataobjectentityofthesametype.Whileatableistwodimensionalinrelationaldatabaseatableinaninmemydatabasecanbemultidimensional.Althoughatwodimensionaltableisdeceptivelysimpletodesignoperatethissimplicityrequi

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